Sometimes an electrical machine may have to be assembled or repaired at its site of normal operation, i.e. in the field conditions. For example, it may be a case that e.g. bearings of the electrical machine have to be changed and it may be too cumbersome and/or costly to move the whole electrical machine to be repaired elsewhere. Especially, installing a rotor of an electrical machine into the bore of the stator core may be a cumbersome task in field conditions. Especially, assembling a permanent magnet electrical machine may be a challenging task even in workshop circumstances because strong forces caused by the permanent magnets complicate the installation of a rotor including the permanent magnets into the bore of the stator core. In conjunction with permanent magnet electrical machines having surface mounted permanent magnets, there is a considerable risk of damaging the permanent magnets when installing the rotor into the bore of the stator core.
Publications CN101577453, JP2003143786, KR20000007669, JP8168215, and JP2223342 disclose various methods for installing permanent magnets into a rotor of a permanent magnet electrical machine. The installing of the permanent magnets into the rotor into correct positions is a challenging task because of the forces caused by the permanent magnets. However, technical solutions are needed also for overcoming the challenges related to installing of a rotor comprising permanent magnets into the bore of the stator core of a permanent magnet electrical machine. As well, the technical solutions are needed for overcoming the challenges related to installing of a rotor into the bore of the stator core of an electrically magnetized electrical machine in field conditions.